Currently, nuclear power plants and thermal power plants take in a large amount of sea water for use as a coolant.
In order to prevent floating foreign objects such as jellyfish from flowing in through a sea water intake, a traveling screen or the like is disposed in front of the water intake. The foreign objects present on a sea surface or in sea water are caught in the screen which is rotatably displaced, and the caught foreign objects and the screen are lifted above the ground for collection.
The collected foreign objects mainly include jellyfish, which are often disposed as a waste.
However, in the event of massive proliferation of jellyfish and a massive inflow of jellyfish due to a flow of tide, the screen tends to be clogged up easily, and water intake is blocked.
Furthermore, since a large amount of jellyfish needs to be disposed as the waste, there is a need to take an environmental consequence into consideration, and a problem is also posed in terms of high disposal cost.
One possibility of addressing the above problems is to prevent entrance of jellyfish by entirely covering a water intake surface, which is an entrance route of jellyfish and the like, by a net (or a mesh material) spreading out in a direction along the water intake surface. However, in practice, the net is clogged up by jellyfish, and water intake to the plant is blocked, possibly resulting in a shutdown of a plant.
The above situation is to be strictly circumvented.
In order to solve the above problem, Patent Literature 1 discloses a device including longitudinal nets spreading out in a surface area of the sea, a bottom net having a triangular shape, and an opening provided between each longitudinal net and the bottom net, for example.
According to the above device, the number of the foreign objects such as jellyfish that reach the water intake is reduced.
Patent Literature 2 also discloses an offshore processing system that retains captured jellyfish in sea water so that the captured jellyfish are killed and then dissolved in sea water.